The 1N6030D: The part is a 180 V Zener diode in a DO-35 axial package, rated for 500 mW continuous power dissipation. The ±1% tolerance is tighter than the standard ±5% you see on most Zeners in this voltage class — useful if you need a stable reference or clamp threshold without trimming.
180 V Zener — where the 500 mW rating matters
At 180 V nominal, the 500 mW power limit means the diode can handle about 2.8 mA continuous before you exceed the dissipation budget (Pmax / Vz). If your circuit needs to sink more current — say for a shunt regulator — you either parallel devices or move to a higher-power package. The 1.7 kOhms Zzt impedance at that current tells you the regulation slope: a 1 mA change in current shifts the Zener voltage by roughly 1.7 V. Reverse leakage is specified at 100 nA maximum with 137 V across the junction — that is 76% of the nominal Zener voltage. For a precision clamp or reference, this low leakage means the diode does not load the node until it reaches the breakdown knee. The -65°C to 175°C operating temperature range covers military and industrial extremes — avionics, downhole tools, or engine-bay electronics where the ambient can hit 125°C and self-heating adds another 50°C margin.
DO-35 axial package — board-fit reality
The DO-35 (DO-204AH) glass body is 0.166 inches long with 0.020-inch diameter leads. Through-hole mounting means the leads need forming for PCB insertion — the glass body is brittle, so bend radius matters to avoid cracking the seal. The 1N6030D ships in Bulk packaging, so you get loose parts, not tape-and-reel. Forward voltage is 1.1 V maximum at 200 mA — that is the conduction drop when the diode is forward-biased. For reverse-polarity protection or clamping, the 200 mA surge rating gives you a rough idea of the non-repetitive peak current the junction can survive before the 500 mW steady-state limit kicks in.